1. Technical Field
The present invention relates to a projector.
2. Related Art
Hitherto, a reflection type projector has been known as one type of liquid crystal projector. For example, the reflection type projector includes an illumination optical system, a polarization beam splitter (hereinafter, referred to as a PBS), a reflection type liquid crystal panel, and a projection optical system. Light emitted from the illumination optical system is incident on the liquid crystal panel via the PBS. The PBS is generally disposed so as to form 45° with the normal direction of the liquid crystal panel. The light incident on the liquid crystal panel is modulated and reflected by the liquid crystal panel. The light reflected by the liquid crystal panel is incident again on the PBS and is split into polarized light for showing an image and polarized light for showing an inverted image. The projection optical system projects the polarized light for showing the image to a screen or the like to display the image.
The PBS according to the related art is configured such that two prisms with a dielectric multilayer film coated on an inclination surface of the right angle prism are adhered on the inclination surfaces. In recent years, a wire grid element having a smaller incident angle dependency of a polarized-light splitting function compared to the PBS according to the related art has been used. Therefore, the contrast ratio of the reflection type projector has been considerably improved (for example, see JP-T-2003-506746, JP-A-2005-250057, JP-A-2004-46156, and JP-A-2000-111839).
In a projector disclosed in JP-T-2003-506746, light emitted from an illumination optical system is reflected from a wire grid element and is incident on a liquid crystal panel and the light for showing an image in the light modulated by the liquid crystal panel is transmitted through the wire grid element and is projected. In a projector disclosed in JP-A-2005-250057, a wire grid element is disposed in a medium with a refractive index greater than 1. In a projector disclosed in JP-A-2004-46156, the contrast ratio can be optimized by rotating a wire grid element around the normal direction. In a projector disclosed in JP-A-2000-111839, since a wire grid element forms an angle greater than 45° with respect to the normal direction of a liquid crystal panel, an incident angle of light emitted from the liquid crystal panel with respect to the wire grid element is less than 45°.
In the projectors, the contrast ratio is expected to be newly improved, and thus the projectors using the above-described wire grid element have a margin for improvement.